Friday, 28 July 2017

Back to their future


It was about two years ago when my enthusiasm for very amateur astronomy got me into trouble (of sorts). Not that I knew it at the time, one often doesn’t. Hindsight is 20:20 they say.
A 360º time-lapse movie of the sky over Blean (north Kent, UK) taken with the skycam at the Beacon Observatory at the University of Kent. The mast on the right is the observatory’s weather station. Despite the local light pollution, it’s possible to make out several constellations as well as the Milky Way (– our Earth-bound view of our own Galaxy; in September, when this sequence was captured, the galactic centre would have been just out of shot). Read on to see how this fits into the post.
I can’t remember a time when the night sky didn’t fascinated me; in some ways one might say that it was my entry point into science. Had it been a subject available at my school I would have chosen it. As it was I had to wait until I was allowed to drive my parents’ car from our village to the nearest large town – in which there was a library running adult education classes in observational astronomy. I’ll never forget the first time, using my small [1] and necessarily inexpensive telescope, I saw the shadows of mountains on the Moon, the phases of Venus, ‘bulges’ on the side of Saturn created by its unresolved rings, and watched the motion of the four Galilean moon of Jupiter. There’s no going back after that. I even tried my hand at astrophotography: in classic ‘Heath-Robinson’ style – a ‘bricolage’ as they might say in France – I built a frame from scraps of wood to hold the telescope and my soviet-made 35 mm camera atop a tripod. It never did work; I couldn’t get the focal distances right. As the years passed by I spent less and less time outside gazing upwards: there were so many other things to focus on. The underlying fascination, however, never went away; more recently it has begun to re-surface – hence this post.
By the age of 13 I was using a notebook to make sketches and describe what I observed – here, what I later learnt were haloes around the Moon caused by high-altitude ice crystals.
A few months before my ‘retirement’ I was given on loan a somewhat larger and more sophisticated telescope [2]. It had been donated to a primary school, where no-one knew how to use it or had the time to find out, and for which no-one could foresee a practicable use given the young age of the pupils. The whole thing had just been re-discovered in a series of boxes in a cupboard somewhere. The idea was that I figure out how to run it and begin to explore what the school might do with it in the longer term. I’m still a long way from completing my task, but I have slowly mastered the basics. It’s too cumbersome to transport it away from my built-up and excessively illuminated neighbourhood, so I rely on the few shadowy spots on my front drive and rear garden for observing sites – and rejoice on those rare occasions when the nearest street lights fail. Thus, the motivation to set it up more fully each time it emerges from my garage is not strong. That notwithstanding, I am beginning to have a lot of fun with it. There’s an inexhaustible list of things to look at, and key goals remaining like viewing our near-neighbour galaxy, Andromeda. However, for now it remains a work in progress, and moves forward at the rate I wish to lose sleep on clear nights. 
My early attempts at photographing what I was looking at using my smartphone were far from impressive, although it was just about doable. However, things have begun to improve considerably now that I have invested in a simple clamp that attaches to the telescope’s eyepiece and holds the ‘phone in place. On the left is, self-evidently, my image of the Moon taken using a green filter; the crater rims near the day/night terminator when the Sun is low in the lunar sky are picked out quite nicely. (With a bit of trigonometry, the shadows provide a means of estimating the height of the mountain ranges; e.g. here.) Jupiter has been easily visible in the months leading to this post as the central image, taken directly using my ‘phone, attests. However, train the telescope onto it and the spot becomes a disk and the four so-called Galilean moons may be seen. I need to go back to this and try again with a suitable colour filter: the moons won’t then be seen, but the equatorial rings on Jupiter – gloriously visible with the eye through the telescope – might emerge in an image.

Now we reach the ‘indiscretion’ with which I began. On a return visit to my old department a colleague, Dirk Froebrich, an extremely talented astronomer/astrophysicist with an interest in star formation, reminded me that I had once asked if I could use the telescope [3] then being installed and commissioned on the edge of campus. He gave me the opportunity of being trained in its operation so that I might help to run their science programme when the core team were unavailable. Apparently, there was a period in June when that situation would arise due to conferences, holidays and trips to use really seriously impressive international observatories (e.g. here). I had no real conception of what I was letting myself in for, but said “yes please” nonetheless.
The telescope and its dome at the time I first volunteered. In the few months since then some additional equipment has been installed.
Apart from anything else, I was attracted by the thought that this would form a part of their ‘citizen science’ programme: school groups, amateur astronomy clubs [4] and their like could enlist to look through the data being collected and thereby perhaps contribute to new discoveries. It sounded genuinely exciting, and still does. The essence of the project, as I understand it in my amateurish way, is to measure the light coming from young stars in some of the star-forming regions of our galaxy. Their timeline starts with the emergence of higher density regions within one of the huge dust/gas clouds that exist; this might have been initiated by the effects of light from nearby stars perhaps. Slowly, these swirling masses begin to pull themselves together under the effect of their own gravity until each has a dense central region surrounded by more dust/gas which is attracted inwards under gravity. Each of these entities is rotating: faster now, because that’s what happens when the diameter decreases – think of an ice skater speeding up as their arms are drawn in to their body. Eventually, the central region may become massive and dense enough for nuclear fusion to begin; a star is born. If smaller regions begin to coalesce in the surrounding disk of dust, its accretion disk, then we may see the development of planets, asteroids etc. Unless, that is, the outward pressure of the light and other emissions from this new star overcomes its gravitational attraction and thereby ‘blows’ the dust away. (There’s quite a narrow window, cosmologically speaking, for planetary formation to begin it seems: unless it’s underway within a few millions years the star will indeed blow the dust in its accretion disk away into the
surrounding galaxy. I have adapted an artist’s impression, shown here.) Now, our young stars don’t collect additional matter from the surrounding disk at a uniform rate it seems. A given star may have periods when its brightness increases quite significantly because the rate at which it is accreting new matter from the surrounding disk has increased markedly. There are theoretical models for all this, but a lack of data. This is where the citizen science project comes in. Light curves are very carefully measured and those measurements repeated over an extended period – every cloud-free night for which they are above the horizon in fact – and a hoped-for army of interested volunteers seek out the tell-tale signs of a sudden change in brightness.

I spent most of a night having the necessary software loaded onto my laptop and taking copious notes as I watched over Dirk’s expert shoulders, and another night with him carefully watching me, driving-instructor-like. Then came the fearful part: running the show myself from my laptop at home. I spent my professional life as a scientist using very expensive, often unique, pieces of equipment in pursuit of new knowledge (e.g. in this earlier post). But, perhaps because this is not my area of expertise or experience, finding myself in sole charge of this £100,000+ observatory for a night felt peculiarly daunting - indeed, downright stressful. Thankully, in the short intervening period I have made mistakes, but damaged nothing. Despite what some might consider the foolishness of actually volunteering to lose sleep, I have continued to learn, which is of course what I wanted to do (- alongside making a positive contribution).
There are a lot of windows to monitor, so I connected my small laptop to my home PC’s screen. On a second, older laptop I had radar images showing cloud-cover over my part of the country – that way I had at least an hour’s warning of approaching poor weather, which gave me time safely to close everything up.
‘The proof of the pudding is in the eating’ as the old saying has it. Shown below are the four images associated with my first full night of observation. They are VRI (i.e. individual colour filtered images, later combined) composites of IC1396A, IC5070, MWSC3274 and NGC7129, about 15min integration in each filter. Each is a region of the nearby galaxy in which star formation is occurring; the dust/gas clouds are clearly visible (e.g. top left). The most distant region is approximately 3300 light years away; we’re therefore photographing and measuring it as it was when Tutankhamen died, the first books were being produced in China and a little before the time of Moses. I was looking back in time from a vantage point which may represent their future.



Footnotes:
[1] A refractor with an aperture of about 30 mm at a guess.
[2] A 102 mm, Maksutov-Cassegrain reflector on a motorised equatorial mount, along with an impressive selection of eyepieces and filters.
[3] This is a beautiful beast: a computer-driven reflector with a mirror aperture of 432 mm (i.e. almost 20 times the mirror area of my borrowed telescope, and of far higher optical quality) and with a 16M pixel cooled CCD camera; further details here. The whole thing sits elegantly within its bespoke observatory dome (also driven remotely via computer), together with its own weather station etc.
[4] Perhaps like the club I visited recently, Ashford Astronomical Society: lovely people, full of enthusiasm and experience – highly recommended. I was invited by a graduate of my old department, Emma, who is a leading member there; she and her husband were jointly, and expertly, giving that evening’s talk.



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